1. Field of the Invention
The invention relates to improvements in the field of charged particle beam emitting devices and pertains particularly to a charged particle beam emitting device which includes at least two separate charged particle beam guns, and to a method for operating a charged particle beam emitting device.
2. Description of the Related Art
Advanced science and technology such as nanotechnology, biology and semiconductor industry places a high demand on charged particle beam emitting devices such as electron microscopes or electron beam writing devices with respect to reliability and performance. As an example, in semiconductor industry scanning electron microscopes are used for the inspection of manufactured semiconductor structures. The inspection is not restricted to the final semiconductor structure but also includes the inspection of intermediate manufacturing steps for the early identification of defective structures. Important aspects in semiconductor manufacturing are the yield and throughput of the manufacturing equipment. Although inspection and process diagnosis of intermediate structures allows the identification of defective semiconductor structures at a very early stage and hence enables the operator of the manufacturing equipment to react instantly, additional inspections also reduce the overall throughput of the manufacturing process. A reduction of any unwanted interruptions and delays of the manufacturing process caused by the testing equipment is therefore highly desired.